1. Field:
The field of the invention is electronic devices for indicating the temperature of the human body.
2. State of the Art:
The shortcomings of conventional expanding liquid medical thermometers include the excessive time (three to four minutes) required, questionable precision and accuracy of the temperature indication, and the necessity for sterilization after use. Busy medical personnel often do not allow sufficient time for these thermometers to reach complete equilibrium readings. Other variables producing inaccuracy include the selection of measurement location upon or within the patient's body, since local body temperatures vary significantly. Even within the mouth, under the tongue, the temperature may vary as much as 1.5.degree. F. from front to rear. Temperatures within the mouth also vary rapidly and significantly from evaporation of mouth fluids, if any air enters from the lips or the throat. Electronic temperature indicator probes have been developed for use within the body, utilizing thermocouples or thermistors as the basic temperature sensing elements. Such probes provide greatly improved (reduced) measuring periods, because of the very low mass of the thermocouple junctions or thermistor elements. Potentially, these junctions reach equilibrium generated electromotive force within small fractions of a second. Unfortunately, the junctions must be protectively housed, adding mass, slowing the measurement to about 1.5 to 2.5 minutes to complete equilibrium. In practice, these probes are generally allowed to remain in temperature sensing position for slightly less than one minute, the true temperature then being predicted from the reading using curves or other correction procedures based on questionable assumptions, often not accounting for the actual temperature measuring conditions. To shorten the temperature measuring time, the housings are of small diameter and elongate, being finely drawn and sharp, unpleasant and even dangerous in use. Sterilization is necessary between uses and the aforesaid variations with temperature sensing location are present.